krehbiel



March 27, 1962 R. D. KREHBIEL 25,147

CONTROL VALVE FOR MULTIPLE VALVE BANKS Original Filed Oct. 27. 1958 4Sheets-Sheet 1 v 6' F90 PUMP T 70 BIA/K ROBERT D. KREHBIEL INVENTOR.

FMM

March 27, 1962 R. D. KREHBIEL 25,147

' CONTROL VALVE FOR MULTIPLE VALVE BANKS Original Filed Oct. 27, 1958 4Sheets-Sheet 2 INVENTOR. ROBERT D. KREHBIEL March 27, 1962 R. D.KREHBIEL 25,147

CONTROL VALVE FOR MULTIPLE VALVE BANKS Original Filed Oct. 27, 1958 4Sheets- Sheet s w an. END 1 ROBERT D. KREHBI EL INVENTOR.

March 27, 1962 R. D. KREHBIEL 25,147

' CONTROL VALVE FOR MULTIPLE VALVE BANKS Original Filed Oct. 27. 1958 4Sheets-Sheet 4 FRO/ I PUMP 7'0 TANK ROBERT D.

United States Patent *Ofiiice Re. 25,147 Reissued Mar. 27, 1962 25,147CONTROL ,VALVE FOR MULTIPLE VALVE BANKS Robert D. Krehbiel, Hutchinson,Kans., assignor to Cessna Aircraft Company, Wichita, Kans., acorporation ofKansas Original No. 2,954,051, dated Sept. 27, 1960, Ser.No. 169,638, Oct. 27, 1958. Application for reissue Sept. .25, 1961,Ser. No. 141,569

13 Claims. (Cl. 137-622) Matter enclosed in heavy brackets appears inthe original patent but forms no part of this reissue specification;matter printed in italics indicates the additions made by reissue.

This invention relates generally to fluid flow control valves and moreparticularly to a spool type control valve particularly designed forcooperative association in a bank of independently operable but similarcontrol valves, whether the bank be made up of separable interchangeablevalve units, or made as a single unitary housing defining multiple spoolbores, certain common and certain individual flow passages, ports,ducts, etc.

Multiple valve banks of this general type are common, and are widelyused to centralize operator control of multiple circuits in hydraulicsystems for road machinery, agricultural machinery, mechanical shovels,etc. The individual valves in such a bank may be designed to controlvarious type of hydraulic servo motors, such as both single and doubleacting working cylinders, vane type rotary actuators, etc. Theindividual valves in such banks have registering transverse throughpassages which together constitute at least one and often two commonpressure fluid passageways through the entire bank from which each valvemay direct pressure fluid to the cylinder or other hydraulic appliancewhich it controls. Each individual valve in such a bank alsoconventionally has two separated transverse through passages, one neareach of its ends, which respectively register with similar passages inthe adjacent valves to form two common fluid return passageways throughthe entire valve bank, and into which each valve may direct return fluidfrom the cylinder or motor which itcontrols.

While the provision of the two mentioned fluid return passagewaysthrough the bank has always been considered necessary, it has at leasttwo decided disadvantages. Duplicate passageways necessarily increasethe overall length of each valve in thesbank. They also seriouslycomplicate the internal design of the various valves in the bank,especially when it is desired to include in-the bank valves whichcontrol double acting cylinders and other valves which control singleacting cylinders, or one or more valves which return fluid to the tankor reservoir through a separate return line rather than through a commonreturn passageway in the bank.

It is a primary object of this invention to provide valves forassociation and cooperation in a bank, which valves include only asingle common fluid return passageway through the bank in conjunctionwith a fluid transfer passage through which fluid may be by-passed fromeither end of the valve to the otherfor purposes which will be fullyexplained herein.

By eliminating one common return passageway through all valves in thebank, my invention makes possible a reduction in the overall length ofeach valve in the bank. In a multipleunit valve bank this reduces thesurface area which must be sealed against similar surface areas ofadjacent valves in the bank, thus reducing possible leakage points. Byshortening the housing it also reduces the chances of warping ordistorting the individual housings, when they are forced together toprovide necessary sealing pressure.

Use of only a single common return passageway through all valves in thebank, in combination with a transfer passage extending along butseparate 'from the valve spool bore, makes it possible for the commonreturn to be connected with various flow passages at a desired locationalong the spool bore and this in turn simplifies valve design. It alsomakes it possible to include a larger number of different types ofvalves in a single bank.

it is an additional object of the invention to provide a valve whichincludes the mentioned common through pressure and return passagewaysand the fluid transfer passage, yet which also may include anindependent fluid return port through which fluid can be returneddirectly to the system reservoir at a pressure which varies mateiiallyfrom the pressure of fluid passing through the single common returnpassageway in the bank, thus eliminating slow return of the plunger of alightly loaded single acting cylinder for instance, due to higher returnpressure in the common return passageway.

Another object is to provide a control valve having the above mentioneddesirable features which may be of either the open or closed centertype, for controlling single acting, double acting and float positioncylinders.

The invention, together with other objects, will be more clearlyunderstood when the following description is read in connection with theaccompanying drawings, in which:

FIG. 1 is a sectional view through a valve bank which includes threeassociated and cooperating valves in series with an end plate at eachend of the bank, each of said valves embodying the invention;

FIG. 2 is a longitudinal central sectional view through an open centerdouble acting control valve, and is taken along the line 22 of FIG. 1;

H65. 3 and 4 are similar sectional views through two different types ofopen center single acting control valves, taken along the lines 3---3and 4-4 respectively of FIG. 1;

FIG. 5 is a similar longitudinal central sectional view through a closedcenter double acting control valve, also embodying the invention; and

HG. 6 is a section view through the valve bank connection plate, and istaken along the line 6--6 of FIG. 1.

Before describing the details of construction and operation of theseveral illustrated valves which embody the invention it should beunderstood that any number of diflferently designed and functioningvalves of the general type before mentioned may be associated in such avalve bank in any sequence. This disclosure is being restricted to thefour types of valves shown for the purposes of clarity and illustrationonly.

Referring to FIG. 1, a control valve bank is illustrated which is madeup of a connection plate 12, a double acting valve 13, a single actingvalve withseparate fluid return 14, a single acting valve 15 which dumpsreturn fluid into a common fluid return passageway, and an end plate 16.These valves arerespective ly illustratedin detail in FIGS. 2, 3, and 4.The individual valve housings are held in assembled relation by bolts 17and O-ring seals :18 between adjacent housings prevent leakage of fluid.

Each housing is provided with a longitudinally disposed annularlygrooved bore which: bores slidably receive valve spools i9, 26, and 21..Each spool is normally maintained in its neutral position, as shown inFIGS. 1

to 5 inclusive by a conventional spring actuated spool centeringmechanism, one of which is shown in detail inis provided with a pressurefluid inlet port 25 which receives fluid from the pump (not shown), anda connecting transverse passage 26 which communicates with short ducts27 and 28. Housing 12 also has a fluid return port 29 which communicateswith a short duct 30. Port 29 is connected to a line leading to a fluidreservoir or tank, not shown.

With all valve spools 19, 20 and 21 in their neutral positions, and withthe pump delivering pressure fluid to the end plate, pressure fluid ispresent in the transverse through pressure passageway made up of therespective transverse communicating ducts 31, 32 and 33, each of whichcommunicates with the spool bore in its respective housing. Alsopressure fluid is flowing from the end plate housing 12 through thecommunicating second through pressure passageway made up of thetransverse staggered neutral by pass ducts 34 to 39 in the respectivevalve housings, through passage 40 in the end plate 16, through thecommon transverse return passageway made up of transverse ducts 41 to 43and thence to the tank through duct 30 and port 29.

IG. 2 VALVECONSTRUCTION Referring to FIG. 2, the housing of valve 13includes a series of axially spaced annular grooves which form chambers44 to 50 all of which communicate with the spool bore 51. Alongitudinally disposed fluid transfer passage 11 aflords communicationbetween chambers 44 and 50. Chamber 50 is of course a part of the commonreturn passageway 41-43.

This valve is designed for control of a double acting working cylinderand is consequently provided with two motor ports 52 and 53, which areconnected respectively to opposite ends of a cylinder to be controlled.The motor ports communicate respectively with lock out check valvechambers 54 and 55 provided with valve seats 56 and 57. The seatscooperate with spring seated check valves 58 and 59 which are providedwith inwardly projecting aligned valve unseating stems 60 and 61.

Communication between chamber 45 and valve seat 56 is afforded by afirst transmission duct 62, while a second transmission duct 63 affordscommunication between chamber 49 and valve seat 57, and hence with motorport 53. It will thus be seen that the transmission ducts 62 and 63serve to transmit fluid between the spool bore 51 and respective pointsof fluid use, in this case to and from the opposite ends of the cylinderto be controlled, as well as to integral pressure chambers utilized forunseating check valves 58 and 59.

The means for unseating check valves 58 and 59 is a reciprocable fluidpressure actuated plunger 64 slidable in a bore 65 of complemental crosssection, the axis of which is aligned with valve stems 60 and 61. Theinner ends of these two stems project into aligned seats in the oppositeends of plunger 64, as clearly shown in FIG. 2.

FIG. 2 VALVE-OPERATION Still referring to valve 13 and to both FIGS. 1and 2 of the drawing, when spool 19 is moved to the left in FIG. 2(inward) spool land 66 moves away from that portion of the spool boreproper which it normally seals. When land 66 has moved far enough to theleft to block communication between chambers 47 and 48, and consequentlybetween ducts 34 and 35 (FIG. 1) pressure builds up in chamber 48 andfluid flows through chamber 49, through transmission duct 63, valve seat57 and port 53 to the connected end of the cylinder (not shown).

As a result of the mentioned inward spool movement, spool land 67 blocksflow of pressure fluid from the pressure passage or duct 34 through thetransfer passage 11 to the first transmission duct 62.

With the spool in its left hand position pressure fluid in the lower endof transmission duct 63 forces plunger 64 to the left, unseating checkvalve 58. Fluid from the opposite end of the cylinder being operated isthus free to return to the tank through port 52, valve seat 56,transmission duct 62, chambers 45- and 44, transfer duct 11, commonreturn passage 41-43 (which includes chamber 50), duct 30, and returnport 29.

Similarly by shifting valve spool 19 outwardly (to the right in FIG. 2)from its neutral position, motor port 52 will be open to the throughpressure passageway 3133, through chambers 46 and 45 and transmissionduct 62. Plunger 64 will be moved to the right in FIG. 2 to unseat checkvalve 59, and motor port 53 will be open to the transmission duct 63,common return passageway 4143 and to the tank. The spool in this righthand position blocks flow of fluid from pressure chamber 46 throughtransfer passage 11 to the other transmission duct 63.

FIG. 3 VALVECONSTRUCTION The FIG. 3 valve is designed for control of asingle acting cylinder, and instead of directing return fluid from thecontrolled cylinder into the common return passageway 41-43 in the valvebank, the returning fluid is discharged into a separate return line (notshown) which is connected directly to the tank, a separate return portbeing provided in the valve housing for this purpose. The separatereturn is a decided advantage in case the cylinder being controlledoperates only a light load and the light load is incapable of forcingfluid from the cylinder into the higher pressure existing in the commonthrough return passageway 4143 in the valve bank.

In common with the described FIG. 2 valve, the FIG. 3 valve includes acorresponding longitudinally disposed fluid transfer passage 72, theopposite ends of which communicate with the spool bore 81 throughenlarged diameter annular chambers 74 and 79. It will be noted that theright hand end of transfer passage 72 does not, in this case, connectwith chamber 80, which constitutes a part of common return passage 4143.

Also in common with the FIG. 2 valve, this FIG. 3 valve includes twooutlet ports, one a fluid return port 82 which is connected by separateline (not shown) to the tank, and the other a motor port 83 which isconnected by line to the cylinder to be controlled. This valve alsoincludes two fluid transmission ducts 92 and 93 which correspond toducts 62 and 63, and serve to transmit fluid between the spool bore 81and respective points of use. In this case transmission duct 93transmits fluid between the bore and the cylinder to be operated, andduct 92 transmits fluid between the bore and the blind chamber formed bythe lower end of the duct itself, at which point the fluid is utilizedto force plunger 94 to the right.

Valve 14 also includes a corresponding series of enlarged diameteraxially spaced annular grooves which form chambers 73 to inclusive, allof which communicate with spool bore 81. A short duct 68 connectschamber 73 with return port 82. Chamber75 connects the spool bore withtransmission duct 92. Chamber 76 communicates with transverse duct 32(FIG. 1) which in turn constitutes a part of the transverse pressurepassageway 3133 through the bank. Similarly, chambers 77 and 78communicate respectively with the transverse ducts 36 and 37, whichconstitute parts of the neutral by-pass pressure fluid passageway 34-39(FIG. 1). Chamber 79 connects spool bore 81 With transmission duct 93..Chamber 80 communicates with transverse through return passageway 31-43(FIG. 1).

Still referring to FIG. 3, motor port 83 and the lower end oftransmission duct 93 are connected through a lockout check valve chamber69 having a seat 70 which cooperates with a spring pressed check valve71. Valve is provided with a valve unseating stem 84, which projectsinto and is aligned with a blind bore 85 in a plunger 86. Plunger 86 isslidable in a bore 87 in the valve housing, and the opposite ends ofthis plunger are subjected to pressure fluid in the two transmissionducts 92 and 93. A cannelured valve spool 20, slidable in bore 81,completes the assembly. The valve spool is spring biased to its neutralposition by means of a spring and washer assembly identical to thatshown in the FIG. 2 valve.

FIG. 3 VALVE-O PERATION When spool 20 is shifted to the left, land 89cuts communication between chambers 77 and '78 and land 90 cutscommunication between chambers 74 and 73. Pressure fluid passes fromchamber 78 through chamber 79, transmission duct 93, valve seat 70 andout through motor port 83 to the cylinder. The spool may be returned toits neutral position and the plunger in the connected working cylinderwill be maintained in its up position because check valve 71 preventsfluid from flowing from the cylinder into transmission duct 93.

To allow the load to return the plunger in the working cylinder to itsinitial position spool 20 is shifted to the right ('FIG. 3) of itsneutral position. Pressure fluid then flows from transverse pressurepassageway 3 1--33 (FIG. 1) through chamber 75 into transmission duct 92to a point of use in the lower end of that duct. The fluid in thetransmission duct exerts force on the left hand end of plunger 86,forcing it to the right and unseating check valve 71 through its stem84.

The load on the working cylinder plunger now forces fluid from thecylinder through motor port '33, through valve seat 70, transmissionduct 93, chamber 79, transfer duct 72, chambers 74 and 73, duct 68 andout through return port 82 to the tm.

With the spool in this right hand position pressure fluid is blocked bylands 89 and 90 from entering the chambers 79 and 74 respectively, atopposite ends of the transfer duct. Spool land 91 prevents returningfluid from entering the transverse through return passageway, becausethe lwd 91 blocks communication between chamber-s 79 and 80.

From the above it will be seen that this valve also utilizes the twotransmission ducts and the transfer passage, as in the FIG. 2 valve, butaccomplishes different results.

FIG. 4 VALVECONSTRUCTION Referring now to FIGS. 1 and 4, theconstruction and operation of valve 15 will now be explained. Valve 15is also an open center valve for controlling a single acting workingcylinder, but is designed to direct fluid returning from the workingcylinder into the common transverse return passageway 41-43 through thebank, rather than into a separate return line, as in the FIG. 3 valve.Here again the combination of the two fluid transmission ducts and thetransfer duct is used to accomplish a different result.

vA comparison of FIGS. 2 and 4 of the drawing will show that thehousings of the two illustrated valves are very similar. The primarydifferences are that motor port 53 and check valve 59 of the FIG. 2valve have been omitted from the FIG. 4 valve.

The internal chamber arrangement includes a longitudinally disposedfluid transfer passage 94 with annular chambers 95 and 96 at itsopposite ends communicating with the spool bore 97, chamber 96 alsoconstituting a par-t of common return passageway 4143. It includesannular chambers 98 and 99 which communicate respectively with twospaced fluid transmission ducts 100 and 101 which correspond to andserve purposes similar to the transmission ducts in the previouslydescribed valves by transmitting fluid between the spool bore andrespective points of use. In this case transmission duct 98 transmitsfluid to and from the single acting Working cylinder to be operated,through a check valve 102, a seat 103 therefor, and a motor port 104.Transmission duct 101 transmits fluid between the spool bore 97 and theblind chamber formed by the lower end of the duct itself, at which pointthe. pressure fluid is utilized to force a plunger 105 to the left tocontact an aligned valve stem :106 and thereby unseat check valve 102.

The valve housing also includes a bore communicating annular chamber 107which constitutes a. part of transverse pressure passageway -3133through the bank. Similarly annular chambers 108 and 109 communicaterespectively with transverseducts 38 and 39 (FIG. 1) which constituteparts of neutral by-pass pressure fluid passageway 3439. A springcentered cannelured valve spool 21 completes the assembly.

FIG. 4 VALVEOPERATION When spool 21 is shifted to the right of itsneutral position pressure chamber 107 is placed in open communicationwith chamber 98. Pressure fluid flows through transmission duct 100,valve seat 103 and motor port 104 to the cylinder or motor to beactuated. There is no flow of pressure fluid elsewhere in the housing.

When spool .21 returns to its neutral position check valve 182 seats andprevents return of fluid from the actuated cylinder thus holding theplunger in that cylinder in the position to which it was moved by thepressure fluid.

When spool 21 is shifted to the left of its FIG. 4 neutral positionchambers 95 and 98 are placed in open communication. Simultaneouslychambers 99 and 109 are placed in open communication and land 110-blocks communication between chambers 96 and 99. Communication betweenchambers 108 and 109 is also blocked by land 111. Pressure fluid flowsto the lower blind end of transmission duct 101 where it exerts pressureon plunger 105, moves that plunger to the left, and thus opens checkvalve 102. Fluid is thus free to flow from the actuated cylinder throughvalve seat 103, transmission duct 100, chambers 98 and '95, transferduct 94, chamber 96 and into the common return passageway 42-43.

FIG. 5 VALVE-CONSTRUCTION FlG. 5 illustrates the invention embodied in aclosed center valve for controlling a double acting cylinder, and likethe previously described valves, it includes a longitudinally disposedfluid transfer passage 112 and cooperating fluid transmission ducts 113and 114. i

It will be understood by those familiar with this art that a pluralityof closed center valves may be associated together in a valve banksimilar to the open center valve bank illustrated in FIG. 1. The termclosed center simply means that the neutral by-pass pressure passagewaymade up of the staggered ducts 34 to 39 in FIG. 1 is eliminated, andthere is no continuous flow of pressure fluid through the valve bank andback through the common transverse return passageway.

The FIG. 5 valve includes two spaced annular chambers 115 and 1.16 whichcommunicate with the opposite ends of transfer passage 112 and with thespool bore 11']. Chamber 116 also communicates with and constitutes apart of the common return passageway through the bank just as chamber 50of the FIG. 2 valve constitutes a part of the common return passageway4143 in. the FIG. 1 valve bank.

The FIG. 5 valve also includes spaced annular chambers 118 and 119 whichcommunicate respectively with transmission ducts 113 and 114 and withthe spool bore. A central transverse through pres-sure duct 120communicates with similar ducts in other valves in the bank (not shown),and serves to deliver pressure fluid to either of the transmission ducts113 or 114 when the valve spool 121 is shifted to the proper position.

This valve is provided with spaced motor ports 122 and 123 which areconnected respectively to opposite ends of a double acting workingcylinder by suitable lines, not shown.

Free flow of return fluid from each motor port-is prevented by springpressed check valves 124 and 125 seated respectively on seats 1'26 and127 which communicate respectively with the lower ends of transmissionducts 113 and 114. The check valves have integral aligned stems 128 and129, respectively, which project into aligned blind bore type seats inthe opposite ends of a free floating plunger 130, the opposite ends ofwhich are exposed to pressure fluid in the respective transmission ducts113 and 114.

FIG. VALVE-OPERATION When spool 121 is shifted to the left of itsneutral position communication is established between pressure duct 120and chamber 119, open communication is maintained bewteen chambers 115and 118, and communication is blocked between chambers 119 and 116.

Pressure fluid flows through transmission duct 114, through valve seat127 by forcing the valve 125 off its seat, through motor port 123 and tothe number 1 end of the working cylinder to be actuated.

Simultaneously pressure fluid in the lower end of transmission duct 114forces plunger 130 to move to the left of its FIG. 5 position. In somoving plunger 130 contacts and moves valve stem 128, unseating valve124.

Fluid from the number 2 end of the working cylinder is thus free to flowinto the valve housing through motor port 122, through valve seat 126,transmission duct 113, chambers 118 and 115, transfer duct 112 and intothe common transverse return passageway in the valve bank throughchamber 116, and thence to the tank or reser- In similar manner shiftingof the valve spool 121 to the right of its neutral position sendspressure fluid from pressure duct 120 to the number 2 end of the workingcylinder, causes check valve 125 to be unseated, and permits fluidreturning from the number 1 end of the working cylinder to flow throughtransmission duct 114 into common return chamber 116. At this timecommunication between chambers 115 and 118 is blocked and transferpassage 112 is thus cut off from pressure fluid.

The flexibility in valve design afforded by the longitudinal transferpassage in each of the described valves will be more clearly understoodif it is realized that the transfer passage not only permits the use ofa single common return passageway through the valve bank, but that thiscommon return passageway may be located at or near either end of thebank. In other words the location of the return passageway is notrestricted to the location shown in FIG. 1.

From the above explanation and description it will be seen that in allfour illustrated embodiments of the invention the fluid transfer passagecommunicates at its opposite ends with the valve spool bore and its endscommunicate through said bore with the respective fluid transmissionducts. Also in each valve the spool is effective in one position toafford flow of pressure fluid from the transverse fluid supply means inthe bank into one transmission duct while blocking the flow of pressurefluid from the fluid supply means through the transfer passage into theother transmission duct; and the spool is effective in a second positionto afford flow of pressure fluid from the fluid supply means into theother transmission duct while blocking the flow of pressure fluid fromthe fluid supply means through the transfer passage into the firstmentioned transmission duct.

It is also a common feature of all said valves that the spool iseffective in a third position to afford communication between at leastone of said transmission ducts and the transfer passage while blockingcommunication between the fluid supply means and both transmissionducts.

Having described the invention with suflicient clarity to enable thosefamiliar with this art to construct and use different types of valvesembodying the invention, I claim:

1. A control valve structure for association and cooperation with othersimilar valves in a valve bank in which the various valves haveregistering transverse through pressure passages which constitutepressure fluid supply means extending through the bank and haveadditional registering transverse through return passages whichconstitute fluid disposal means extending through the bank, said controlvalve structure comprising: a housing having a longitudinally disposedvalve spool receiving bore therein; annular grooves constituting spacedchambers surrounding and communicating with said bore; transversepassages communicating with said bore through at least one of saidchambers and arranged to cooperate in providing pressure fluid supplymeans through all housings in the bank; a fluid return passage in thehousing [communicating with said bore]; first and second transmissionducts in the housing communicating with said bore at longitudinallyspaced locations, and constituting means to transmit fluid between saidbore and respective points of use; a longitudinally disposed fluidtransfer passage in the housing communicating at its opposite ends withsaid bore, said opposite ends being positioned to communicate throughsaid bore with the respective transmission ducts, said transfer passagealso being in communication with the fluid return passage; and acannelured valve spool reciprocable in said bore, said spool beingeffective in a first position to establish communication between thefluid supply means and the first transmission duct While blockingcommunication between the fluid supply means and the second transmissionduct; said spool being effective in a second position to establishcommunication between the fluid supply means and the second transmissionduct while blocking communication between the fluid supply means and thefirst transmission duct, and effective in at least one of said positionsto simultaneously establish communication, via the transfer passage,between the return passage and that transmission duct which is at thattime blocked from communication with the fluid supply means.

2. The valve described in claim 1 in which the spool is effective in athird and neutral position to afford communication between at least oneof said transmission ducts and the transfer passage While blocking theflow of fluid from the fluid supply means into either transmission duct.

3. The valve described in claim 1 in which one end of said fluidtransfer passage and at least one of said transmission ducts aresimultaneously in open communication with said return passage,regardless of spool position.

4. A control valve structure for association and cooperation with othersimilar valves in a valve bank in which the various valves haveregistering transverse through pressure passages which constitutepressure fluid supply means extending through the bank and haveadditional registering transverse through return passages whichconstitute fluid disposal means extending through the bank, said controlvalve structure comprising: a housing having a longitudinally disposedvaive spool receiving bore therein; transverse passages in the housingcommunicating with said bore and arranged to cooperate With similarpassages in other housings to provide pressure fluid supply meansextending through the bank; a fluid return passage in the housingcommunicating with said bore; a fluid outlet port in the housing; afluid transmission duct affording communication between the bore andsaid outlet port; a longitudinally disposed fluid transfer passagecommunicating at its opposite ends with said bore, said transfer passagecommunicating through the bore with said transmission duct and with saidreturn passage; and a cannelured valve spool slidable in said bore andeifective in a first position to afford communication between the fluidsupply means and said outlet port through said transmission duct,effective in a second position to afford flow of fluid from said outletport through said transmission duct and through the transfer passageinto the return passage, and efiective in a third and neutral positionto block communication between the fluid supply means and saidtransmission duct.

5. The valve described in claim 4-, and a, spring seated check valveinterposed between said outlet port and said transmission duct andnormally preventing flow of fluid from said outlet port into saidtransmission duct; and means responsive to movement of said spool intosaid second position to open said check valve.

6. A control valve structure for association and cooperation with othersimilar valves in a valve bank in which the various valves haveregistering transverse through pressure passages which constitutepressure fluid supply means extending through the bank and haveadditional registering transverse through return passages whichconstitute fluid disposal means extending through the bank, said controlvalve structure comprising: a housing having a longitudinally disposedvalve spool receiving bore therein; annular grooves constituting spacedchambers surrounding and communicating with said bore; transversepassages communicating with said bore through at least one of saidchambers and arranged to cooperate in providing pressure fluid supplymeans through all housings in the bank; a fluid return passage in thehousing communicating with said bore; first and second transmissionducts in the housing communicating with said bore at longitudinallyspaced locations, and constituting means to transmit fluid between saidbore and respective points of use; a longitudinally disposed fluidtransfer passage in the housing communicating at its opposite ends withsaid bore, said opposite ends being positioned to communicate throughsaid bore with the respective transmission ducts, said transfer passagealso being in communication with the fluid return passage; and acannelured valve spool reciprocable in said bore, said spool beingeffective in a first position to establish communication between thefluid supply means and the first transmission duct, between the secondtransmission duct and one end of the transfer duct, and between thesecond transmission duct and the return passage, while blockingcommunication between the first transmission duct and the adjacent endof the transfer passage; said spool being effective in a second positionto establish communication between the fluid supply means and the secondtransmission duct, between the first transmission duct and one end ofthe transfer duct, and between the first transmission duct and thereturn passage, while blocking communication between the secondtransmission duct and the adjacent end of the transfer passage.

7. A control valve structure for association and cooperation with othersimilar valves in a valve bank in which the various vaives haveregistering transverse through pressure passages which constitutepressure fluid supply means extending through the bank and have[addtional] additional registering transverse through return passageswhich constitute fluid disposal means extending through the bank, saidcontrol valve structure comprising: a housing having a longitudinallydisposed valve spool receiving bore therein; transverse passages in thehousing communicating with said bore and with similar passages inadjacent similar housings to provide pressure fluid supply means for thebank and to provide a single fluid return passageway for the bank; [apair of] first and second longitudinally spaced fluid outlet ports; [apair of] first and second longitudinally spaced fluid transmission ductsin the housing aifording communication between the respective outletports and said bore; a longitudinally disposed fluid transfer passagecommunicating at its opposite ends With the bore, and through the borewith the respective transmission ducts, one end of said transfer passagealso being in communication with the return passageway; and a canneluredfluid flow controlling valve spool shiftable in said bore and effectivein a first position to block communication between the firsttransmission duct and the return passageway and between the firsttransmission duct and the transfer passage, and to afford flow of fluidfrom the fluid supply mean outward through the first outlet port via thefirst transmission duct, while simultaneously affording inward flow offluid from the second outlet port through the connected secondtransmission duct and through the transfer passage into the singlereturn passageway; said spool being effective in a second position toblock communication between the second transmission duct and the returnpassageway via the transfer passage, and to afford outward flow of fluidfrom the fluid supply means through the second outlet port via thesecond transmission duct, while affording inward flow of'fluid from the[second] first outlet port through the [second] first transmission ductinto the single return passageway.

8. The valve described in claim 7, and two normally closed checkvalvesin the housing located and oriented to afford fluid flow outwardfrom the fluid supply through the respective outlet ports, and tonormally prevent reverse inward flow therefrom; and fluid pressureactuated means responsive to movement of the spool into said firstposition to open that check valve which controls flow through the secondoutlet port, and responsive to movement of the spool into said secondposition to open that check valve which controls flow through the firstoutlet port.

9. The valve described in claim 8 in which each check valve is providedwith a stem, and the two stems project toward each other in substantialalignment, and the fluid pressure actuated means is a floating plunger,said plunger being reciprocably mounted in an open ended bore whichexposes the opposite ends of the plunger to pressure fluid in therespective transmission ducts, said plunger being located between and insubstantial alignment with said valve stems to contact and move eitherof them to unseat the respective valves.

10. A control valve structure comprising a plurality of similar valvehousings cooperatively associated in a bank, each having a longitudinalvalve spool receiving bore communicating with a plurality of transversepassages so spaced and arranged as to form continuous pressure fluidsupply means extending through the structure as well as a singlecontinuous fluid return passage extending through the structure, saidreturn passage being located near respectively adjacent ends of therespective housings; ports in the housings, one near that end of eachhousing remote from said fluid return passage, each port communicatingwith the bore in its housing; a longitudinally disposed fluid transferpassage in each housing communicating at its opposite ends with the borein its housing, one end of each transfer passage also communicating withsaid return passage, and the other end thereof being positioned tocommunicate through the bore with the remote port in its housing; and acannelured flow controlling spool reciprocable in the bore of eachhousing, each spool being effective in one position to afiord flow offluid from the said port in its housing through its respective transferpassage into said return passage, while blocking communication betweenthe fluid supply means and said port, and between the fluid supply meansand the transfer passage in its housing. 7

ll. A control valve adapted for inclusion in a multiple unit valve bankcomprising: a housing having a longitudinal valve spool receiving bore;a transverse through pressure passage in the housing; a transversethrough return passage in the housing, both said passages communicatingwith said bore and with similar passages in adjacent similar housings toprovide continuous pressure and return passageways through the bank; amotor port and a separate fluid return port in said housing, bothcommunicating with said bore; a longitudinally disposed fluid transferpassage in the housing communicating at its opposite ends with said boreand affording fluid flow between the two ports; a cannelured fluid flowcontrolling valve spool reciprocable in said bore, said spool beingeffective in one position to connect the pressure passage and the motorport and to simultaneously block communication between the two ports viathe transfer passage, and effective in a second position to connect thetwo ports via the transfer passage while blocking the pressure passagefrom both ports, and efiective in all its permitted positions to blockcommunication between the transverse through return passage and bothsaid ports.

12. The valve described in' claim 11, and a spring seated check valveinterposed between the motor port and the bore, and normally preventingflow of fluid from the motor port to the fluid return port via thetransfer passage; and means responsive to movement of said spool intosaid second position to unseat said check valve to afford flow of fluidfrom the motor through the transfer passage and out through the fluidreturn port.

13. In a contol valve structure in which two or more similar valvehousings are cooperatively associated in a bank, each housing having alongitudinal valve spool receiving bore, the structure also having aplurality of bore communicating transverse passages in the housings sospaced and arranged as to cooperate with each other to form continuouspressure fluid supply means extending through the bank, said structurealso having one or two motor ports in each housing communicating withthe respective bores, one port in each housing beinglocated near thatend thereof which is adjacent the corresponding and similarly ported endof each other housing, each housing being provided with a canneluredvalve spool recipr'ocable in the housing bore and effective when movedto a first position therein to afford fluid flow from said supply meansoutward through said one port, the combination with the describedstructure of bore communicating transverse passages in the housings sopositioned as to communicate with each other and with the respectivehousing bores to form a single continuous fluid return passage extendingthrough the bank; a longitudinally disposed fluid transfer passage ineach housing communicating at its opposite ends with the bore in itshousing, one end of each transfer passage also communicating with saidreturn passage and the other end thereof being positioned to communicatethrough the bore with the said one port in its housing, the spool ineach housing being effective when moved to a second position to affordflow of fluid from the said one port in its housing into and through itsrespective transfer passage into said return passage while blockingcommunication between the fluid supply means and said one port andbetween the fluid supply means and the transfer passage in its housing.

References Cited in the file of this patent or the original patentUNITED STATES PATENTS 2,247,141 Twyman June 24, 1941 2,517,153 Wood Aug.1, 1950 2,586,932 Gardiner et a1. Feb. 26, 1952 2,689,585 Presnell Sept.21, 1954 2,707,867 Ruhl May 10, 1955

